metamorphic
Anthracite Coal
Anthracite
Hardness: 2.5-3.0 Mohs; Color: Iron-black to jet black; Luster: Sub-metallic to vitreous (glassy); Structure: Amorphous/Non-crystalline; Fracture: Conchoidal; Specific Gravity: 1.3-1.8
- Hardness
- 2
- Color
- Iron-black to jet black
- Luster
- Sub-metallic to vitreous (glassy)
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Physical properties
Hardness: 2.5-3.0 Mohs; Color: Iron-black to jet black; Luster: Sub-metallic to vitreous (glassy); Structure: Amorphous/Non-crystalline; Fracture: Conchoidal; Specific Gravity: 1.3-1.8
Formation & geological history
Formed through the pro-grade metamorphism of bituminous coal under extreme heat and pressure, typically during mountain-building events (orogenies). Most deposits date back to the Carboniferous period, approximately 300 to 360 million years ago.
Uses & applications
Primary use is for domestic heating and industrial fuel due to its high carbon content and energy density. It is also used in water filtration systems and as a pigment for artists (carbon black).
Geological facts
Anthracite is the highest rank of coal, containing 86%-98% carbon. It burns with a short, blue, smokeless flame. It is sometimes known as 'hard coal' or 'black diamond' because of its high energy value and hardness compared to other coals.
Field identification & locations
Identify in the field by its deep black color, shiny/metallic luster, and its lightweight feel (low density). It will not rub off on your fingers like charcoal or graphite. Common in East Pennsylvania, USA, South Wales, and parts of China.
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